In this tutorial you will learn how to use Enterprise Manager Express to explore the structure of your database. In addition, you will learn how to make a number of changes to your database storage structure.
Time to Complete
Approximately 1 hour
An Oracle database is made up of physical and logical structures. Physical structures are visible in the operating system. An example of a physical structure is an operating system file that stores data on a disk. Logical structures are defined and known to the Oracle Database server, but are not known to the operating system. An example of a logical structure is a tablespace. In this tutorial you will view logical structures in your database and understand how they relate to physical structures in the operating system.
The following is a list of software requirements:
- Oracle Database 12c
Before starting this tutorial, you should have:
- Installed Oracle Database 12c
Viewing Database Storage Structure Information
An Oracle database is made up of physical and logical structures. Physical structures are defined in the operating system. Physical files that store data on a disk are an example of a physical structure. Logical structures are defined in the database and are not known in the operating system. To view storage structure information, perform the following steps:
Viewing Control File Information
Viewing Online Redo Log Information
Viewing Archived Redo Log Information
Viewing Tablespace and Data File Information
Creating a Tablespace
A database is divided into logical storage units called tablespaces, which group related logical structures such as tables, views, and other database objects. A number of tablespaces are automatically created when you create the database. To create a new tablespace, perform the following steps:
Modifying a Tablespace
This section shows you how to configure a tablespace to automatically extend when it reaches the defined limit. To configure a tablespace to automatically extend, perform the following steps:
Managing the Online Redo Log
The online redo log files contain entries that are used to recover transactions in the event of an instance failure and may also be used in recovery from media failure. To ensure that redo entries are not lost in the event of a disk drive failure, redo log files should be multiplexed so that each group has multiple members.To multiplex the redo log file, perform the following steps:
Managing Undo Data
Oracle Database uses undo data to roll back transactions, to provide read consistency, as part of database recovery, and to enable features such as Oracle Flashback Query. Oracle Database automatically ensures that undo data that is in use by an active transaction is never overwritten until that transaction has been committed. The database server maintains and automatically tunes an undo retention period to ensure the success of Oracle Flashback features and for read consistency for long-running queries. Auto-tuning of the undo retention period is enabled when you create your database. To view undo data information, perform the following steps:
In this tutorial, you have learned how to:
- View database storage structure information
- Create and modify a tablespace
- Manage the online redo log
- Manage undo data
- Oracle Database 2 Day DBA 12c Release 1 (12.1)
- Lead Curriculum Developer: Donna Keesling
- Other Contributors: Bert Rich
To help navigate this Oracle by Example, note the following:
- Hiding Header Buttons:
- Click the Title to hide the buttons in the header. To show the buttons again, simply click the Title again.
- Topic List Button:
- A list of all the topics. Click one of the topics to navigate to that section.
- Expand/Collapse All Topics:
- To show/hide all the detail for all the sections. By default, all topics are collapsed
- Show/Hide All Images:
- To show/hide all the screenshots. By default, all images are displayed.
- To print the content. The content currently displayed or hidden will be printed.
To navigate to a particular section in this tutorial, select the topic from the list.